SMD HELP

[Biggtank]

Hello..I am repairing a Memphis 16-MCA3004 amplifier..I have found two smd's that are defective,but can't cross-reference their markings. One is marked 3B horizontal with J vertical,and the other is marked C3 horizontal ,with 2C vertical.Any help will be greatly appreciated🙂

 

[kds9591]

SMD CodeBook

Here's one link to a SMD CodeBook. There are others on the web if you do a search.

The SMD Code Book

 

[Perry Babin]

What is the circuit board designation for these?

 

[Biggtank]

Perry..they are the power fet driver transistors...on the vertical board Q708,and Q709

 

[Perry Babin]

Are you sure that both have a Q prefix?

The C3 is likely a diode and would have a D prefix.

http://www.datasheetcatalog.org/datasheet/kec/KDS122.pdf
http://datasheet.octopart.com/BC856BLT1G-ON-Semiconductor-datasheet-7834531.pdf

 

[Biggtank]

Correct Perry c3 does have a d prefix....

 

[Biggtank]

Thanks Perry,for the help..I also found this very helpful site.
Marking smd

 

[Perry Babin]

The diodes likely survived. I'd use MMBTA56s as replacements for the transistors.

 

[Biggtank]

Actually..the diodes are functioning properly...the transistors are what failed...